But 41-year-old marketing consultant Amy Westrup of Whitefish Bay calls the chance to overturn the 2010 election result "the ultimate mulligan." She voted for Milwaukee Mayor Tom Barrett, one of four Democrats vying for the chance to unseat Walker in the general election on June 5.

The others are Kathleen Falk, Secretary of State Doug La Follette and state Sen. Kathleen Vinehout. Gladys Huber is a Republican running as a Democrat.

Walker faces token opposition in the GOP primary from Arthur Kohl-Riggs, a Walker opponent running as a Republican.

Lt. Gov. Rebecca Kleefisch and three Republican state senators also face recall elections. There is an election in a fourth Senate district where the Republican incumbent resigned.

Polls are open in Wisconsin for a primary election that will determine who will take on the first-term governor in a historic recall election next month.

Milwaukee Mayor Tom Barrett and former Dane County Executive Kathleen Falk are 2 of 4 Democrats on Tuesday's ballot who are looking to challenge Walker in the June 5 general election that has become a nationally watched battle over union rights. Since his successful push to effectively end collective bargaining rights for most state workers, Walker has emerged as a national conservative hero.

Other Democrats on the ballot are Secretary of State Doug La Follette and state Sen. Kathleen Vinehout. Gladys Huber is a Republican running as a Democrat.

Walker faces token opposition in the GOP primary from Arthur Kohl-Riggs, a Walker opponent running as a Republican.

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